Touch sensor devices (also commonly called proximity sensors, touch screens, tablets, or touch pads) are widely used in a variety of electronic systems. A touch sensor device is a device that typically includes a sensing region that uses capacitive, resistive, inductive, optical, acoustic, or other technology to determine the presence, proximity, location and/or motion of one or more fingers, styli, and/or other objects. The touch sensor device, operated with one or more fingers and/or other objects, can be used to provide an input to the electronic system. For example, touch sensor devices are used as input devices for larger computing systems, such as desktop and notebook computers, as well as kiosks and other terminals. Touch sensor devices are also used in smaller devices, including handheld systems such as personal digital assistants (PDAs) and communication systems such as wireless telephones and text messaging devices. Increasingly, touch sensor devices are used in multimedia systems or their remote controls, such as CD, DVD, MP3 or other media recorders or players.
Examples of capacitive touch sensor devices are described in U.S. Pat. No. 5,880,411, entitled “Object Position Detector with Edge Motion Feature and Gesture Recognition,” and U.S. Publication No. U.S. 2004/0252109 A1, entitled “Closed-loop sensor on a solid-state object position detector,” which are hereby incorporated by reference. Examples of inductive touch sensor devices include what is described in U.S. Pat. No. 6,249,234, entitled “Position detector,” which is also hereby incorporated by reference.
Many electronic systems include (or interact with other systems that include) a user interface, or UI, and an input device for interacting with the UI (e.g., interface navigation). A typical UI includes a screen for displaying graphical and/or textual elements. The increasing use of this type of UI has led to a rising demand for touch sensor devices as input devices. Specifically, many typical UIs are implemented under the assumption that the user has the ability to easily perform several important types of inputs. In these applications the touch sensor device can function as a cursor control/pointing device, selection device, scrolling device, graphics/character/handwriting input device, menu navigation device, gaming input device, button input device, keyboard and/or other input device.
In general, scrolling allows users to navigate through relatively large sets of data. For example, scrolling allows a user to move through an array of data to select a particular entry. As another example, scrolling allows a user to bring particular sections of a large document into view on a display screen that is too small to view the entire document at once. In a system with a traditional graphical UI, programs for navigating documents typically include one or more scrollbars to facilitate scrolling through the document. Scrollbars are relatively effective when used with traditional input devices, such a computer mouse or trackball. However, using them with different input devices, particularly touch sensor devices, can require a significant level of attention and dexterity. In addition, scrollbars can be accidentally actuated and take up space on the graphical UI that can otherwise be used for displaying other images, information, or controls.
Various attempts have been made to facilitate scrolling functions using a touch sensor device. One technique, for example, creates a “jog dial” at a set location on a pen-actuated area of a touch screen. In these systems, pen motion around the center of the jog dial is used to cause scrolling at a rate proportional to the rate of angle subtended by the pen as it moves around the center of the dial. Jog dial scrolling can offer significant usability improvement. However, the set location of the jog dial can make input awkward, and the idea of scrolling at a rate proportional to the rate of angle subtended is conceptually difficult, and training naïve users in its use is non-trivial. In addition, the jog dial can be accidentally actuated and takes up space on the graphical UI that can otherwise be used for displaying other images, information, or controls.
Another attempt to facilitate scrolling functions using a touch sensor device is the traditional capacitive scroll wheel found in commercially available media players such as the second generation APPLE IPOD® sold in 2002. In such a system with a traditional scroll wheel, the touch sensor device is configured to allow users to scroll in one continuous motion as opposed to multiple, distinct strokes. This scrolling capability is useful for small, portable devices like cell phones and MP3 players where real estate available for displaying a large amount of information is more limited and thus effective scrolling through the information more desirable, and for accommodating multiple input devices such as volume controls, four-way joysticks, and jog dials can be difficult. However, the traditional capacitive scroll wheel can be accidentally actuated and takes up significant surface area on the electronic system that can otherwise be allotted to other elements, displays, or controls.
Thus, while many different techniques have been used to facilitate scrolling, there remains a continuing need for improvements in device usability. Particularly, there is a continuing need for improved techniques for facilitating scrolling with touch sensor devices.